Showing papers in "Ibis in 2006"
TL;DR: The potential effects of the proposed increase in wind energy developments on birds are explored using information from studies of existing wind farms, and the requirements for assessing the impact of future developments are summarized.
Abstract: The potential effects of the proposed increase in wind energy developments on birds are explored using information from studies of existing wind farms. Evidence of the four main effects, collision, displacement due to disturbance, barrier effects and habitat loss, is presented and discussed. The consequences of such effects may be direct mortality or more subtle changes to condition and breeding success. The requirements for assessing the impact of future developments are summarized, including relevant environmental legislation and appropriate methods for undertaking baseline surveys and post-construction monitoring, with particular emphasis on the rapidly developing area of offshore wind farm assessments. Mitigation measures which have the potential to minimize impacts are also summarized. Finally, recent developments in the monitoring and research of wind energy impacts on birds are outlined and some areas for future work are described.
558 citations
TL;DR: In this paper, the potential impacts of anthropogenic climatic changes upon avian species richness in the two continents of Europe and Africa have been assessed for a range of general circulation model projections of late 21st century climate lead to the conclusion that the impacts upon birds are likely to be substantial.
Abstract: Potential climatic changes of the near future have important characteristics that differentiate them from the largest magnitude and most rapid of climatic changes of the Quaternary. These potential climatic changes are thus a cause for considerable concern in terms of their possible impacts upon biodiversity.
Birds, in common with other terrestrial organisms, are expected to exhibit one of two general responses to climatic change: they may adapt to the changed conditions without shifting location, or they may show a spatial response, adjusting their geographical distribution in response to the changing climate. The Quaternary geological record provides examples of organisms that responded to the climatic fluctuations of that period in each of these ways, but also indicates that the two are not alternative responses but components of the same overall predominantly spatial response. Species unable to achieve a sufficient response by either or both of these mechanisms will be at risk of extinction; the Quaternary record documents examples of such extinctions.
Relationships between the geographical distributions of birds and present climate have been modelled for species breeding in both Europe and Africa. The resulting models have very high goodness-of-fit and provide a basis for assessing the potential impacts of anthropogenic climatic changes upon avian species richness in the two continents. Simulations made for a range of general circulation model projections of late 21st century climate lead to the conclusion that the impacts upon birds are likely to be substantial. The boundaries of many species’ potential geographical distributions are likely to be shifted 1000 km. There is likely to be a general decline in avian species richness, with the mean extent of species’ potential geographical distributions likely to decrease. Species with restricted distributions and specialized species of particular biomes are likely to suffer the greatest impacts. Migrant species are likely to suffer especially large impacts as climatic change alters both their breeding and wintering areas, as well as critical stopover sites, and also potentially increases the distances they must migrate seasonally.
Without implementation of new conservation measures, these impacts will be severe and are likely to be exacerbated by land-use change and associated habitat fragmentation. Unless strenuous efforts are made to address the root causes of anthropogenic climatic change, much current effort to conserve biodiversity will be in vain.
239 citations
TL;DR: In this paper, the authors stress the importance of common data collection protocols, sharing of information and experience, and accessibility of results at the international level to better improve our predictive abilities.
Abstract: European legislation requires Strategic Environmental Assessments (SEAs) of national offshore wind farm (OWF) programmes and Environmental Impact Assessments (EIAs) for individual projects likely to affect birds. SEAs require extensive mapping of waterbird densities to define breeding and feeding areas of importance and sensitivity. Use of extensive large scale weather, military, and air traffic control surveillance radar is recommended, to define areas, routes and behaviour of migrating birds, and to determine avian migration corridors in three dimensions. EIAs for individual OWFs should define the key avian species present; as well as assess the hazards presented to birds in terms of avoidance behaviour, habitat change and collision risk. Such measures, however, are less helpful in assessing cumulative impacts. Using aerial survey, physical habitat loss, modification, or gain and effective habitat loss through avoidance behaviour can be measured using bird densities as a proxy measure of habitat availability. The energetic consequences of avoidance responses and habitat change should be modelled to estimate fitness costs and predict impacts at the population level. Our present ability to model collision risk remains poor due to lack of data on species-specific avoidance responses. There is therefore an urgent need to gather data on avoidance responses; energetic consequences of habitat modification and avoidance flights and demographic sensitivity of key species, most affected by OWFs. This analysis stresses the importance of common data collection protocols, sharing of information and experience, and accessibility of results at the international level to better improve our predictive abilities.
194 citations
TL;DR: In this article, a comparison of large-scale roadside counts (8353 km) through Burkina Faso, Mali and Niger, conducted in 1969-73, were repeated 30-35 years later with the same observer and methodology and at the same season.
Abstract: Comparative large-scale roadside counts (8353 km), through Burkina Faso, Mali and Niger, conducted in 1969-73, were repeated 30-35 years later with the same observer and methodology and at the same season. The transect was divided into three geographical zones and between protected and unprotected areas. All diurnal raptors were recorded (22 801 individuals), as well as large game birds. Large vultures suffered a dramatic decline (98%) outside protected areas. The Hooded Vulture Necrosyrtes monachus population also collapsed in some regions, but survived in central Burkina Faso. Conversely, their abundance index did not decrease significantly in national parks. Four eagle species decreased by 86-93% and seven were not even recorded in the later study outside protected areas; by contrast, in national parks, only three species had declined marginally. Smaller Accipitridae (kites, goshawks, buzzards) also exhibited significant declines outside but not within national parks where woodland species reached their highest densities. The Common Kestrel Falco tinnunculus, mostly European migrants, declined sharply everywhere. African falcons decreased only outside protected areas. Among Palearctic migrants, Montagu's Circus pygargus and Pallid Harriers C. macrourus decreased significantly, Short-toed Eagle Circaetus gallicus less markedly, and Marsh Harrier Circus aeruginosus and Booted Eagle Hieraaetus pennatus not at all. Similar trends had previously been documented in Cameroon. They are associated with human population growth and development, global habitat degradation and ecosystem impoverishment (woodcutting, agricultural intensification, overgrazing, desertification). Heavy use of pesticides, control of locust outbreaks and overhunting have suppressed major food sources. Vultures may suffer from a shortage of carcasses, poisoning for predator control or persecution for trade of meat and body parts. Protected areas play a prominent role in the maintenance of vulture and eagle populations, even though they currently cover less than 2% of the Sudan zone and are virtually absent in the Sahel.
194 citations
TL;DR: It is demonstrated that, especially under poor visibility, terrestrial birds are attracted by illuminated offshore obstacles and that some species collide in large numbers, and actions to make wind turbines more recognizable to birds are suggested, as the most appropriate mitigation measures.
Abstract: Worldwide, Germany is the leading country in the use of wind energy. Since sites for the erection of wind turbines became scarce on land, ambitious plans for the offshore regions have arisen. There have been applications for 33 sites within the German Exclusive Economic Zone in the North and Baltic Seas, some of which entail several hundred individual turbines. Eleven pilot projects are approved, and two others rejected. As several hundred million birds cross the North and Baltic Seas at least twice every year, the Offshore Installations Ordinance says that licensing will not be given if the obstacles jeopardize bird migration. Birds are potentially endangered by offshore wind farms through collisions, barrier effects and habitat loss. To judge these potential risks, the occurrence of birds in space and time as well as details on their behaviour in general (migration, influence of weather) and their behaviour when facing wind farms (flight distances, evasive movements, influence of light, collision risk) need to be determined. Furthermore, the influences of construction and maintenance works must be considered. Since 2003, we have investigated year-round bird migration over the North Sea with regard to offshore wind farms. The main objectives were to assess data on the aforementioned aspects of bird migration over sea. These data can contribute to, for example, estimations of collision risks at offshore wind farms, the possible impacts on bird populations and possible mitigation measures. Results from measurements with different techniques, including radar, thermal imaging, and visual and acoustic observations, were compiled. The findings confirm that large numbers of diurnal and nocturnal migrants cross the German Bight. Migration was observed all year round but with considerable variation of intensity, time, altitude and species, depending on season and weather conditions. Almost half of the birds fly at ‘dangerous’ altitudes with regard to future wind farms. In addition, the number of individuals in reverse migration is considerable, which increases the risk of collision. We demonstrated that, especially under poor visibility, terrestrial birds are attracted by illuminated offshore obstacles and that some species collide in large numbers. Passerines are most frequently involved in collisions. Even if the findings regarding collisions at a research platform cannot be directly applied to offshore wind farms, they do show that on a few nights per year a large number of avian interactions at offshore plants can be expected, especially in view of the number and planned area of projected wind farms. We suggest abandonment of wind farms in zones with dense migration, turning off turbines on nights predicted to have adverse weather and high migration intensity, and actions to make wind turbines more recognizable to birds, including modification of the illumination to intermittent rather than continuous light, as the most appropriate mitigation measures. We further conclude that a combination of methods is necessary to describe the complex patterns of migration over the sea. The recordings are to be continued with the aim of refining the results presented here, and of developing a model for ‘forecasting’ bird migration over the German Bight. We expect more information on avoidance behaviour and collisions after the construction of a pilot wind park.
173 citations
TL;DR: It is concluded that most studies indicate that displacement of raptors appears to be negligible, although some notable exceptions occur and more research is needed, and recommendations for potential improvements are made.
Abstract: Government targets on renewable energy coupled with anthropogenic constraints on development have resulted in a surge in proposals to locate wind farms in upland areas, where they may conflict with the wellbeing of scarce or rare bird species including raptors. European and UK legislation demand that the effects of wind farm developments, both individually and in combination, be assessed to determine the level of impact on these species. The principle adverse effects of wind farms on raptors, as for other terrestrial birds, potentially involve disturbance (displacement or barrier impacts) or collision fatality. Few long-term studies on such effects of wind farms have been undertaken. We review available research results on displacement of raptors, which primarily involve foraging birds, and conclude that most studies indicate that displacement appears to be negligible, although some notable exceptions occur and more research is needed. There is also a need for better understanding of the numbers of birds likely to be killed through collision with turbine rotors at the site level in order to inform planning decisions, although models of bird distribution at several spatial scales can be used to circumvent potential difficulties when locating turbines. Modelling approaches have also been developed that attempt to quantify the theoretical risk of collision. One such approach, the Band model, is a valuable tool for impact assessment and its use is now widespread in the UK. However, there are practical problems associated with gathering the data required to run the model and numerous assumptions must be made concerning bird behaviour. This can lead to deficiencies in the input parameters which potentially have a large effect on the model outputs. Hence, we make recommendations for potential improvements, such as quantifying error in flight height estimation, training of observers in acuity skills, quantifying bird detection-distance functions, and research on factors influencing activity budgets and flight behaviour. In addition, the model outputs are usually adjusted to take account of turbine avoidance by birds and this aspect of birds’ behaviour is poorly understood. As a result of these limitations, collision predictions are only indicative, and more reliable in some situations, and for some species, than others.
159 citations
TL;DR: This paper examines critically the estimation and use of avoidance rates in conjunction with the collision risk model (CRM) and the sensitivity of predicted mortality to errors in estimated avoidance rates is assessed in three studies that have used the CRM.
Abstract: The model of Band et al. (2005) used data describing the structure and operation of the turbines: number of blades; maximum chord width and pitch angle of blades; rotor diameter; and rotation speed; and of bird size and flight: body length; wingspan; flight speed; flapping; or gliding flight, to derive a probability of collision. This approach was found to be generally sound mathematically (Chamberlain et al. 2005). Sensitivity analysis suggested that key parameters in determining collision risk were bird speed, rotor diameter and rotation speed, although variation in collision risk was still small within the likely range of these variables. Mortality is estimated by multiplying the collision probability by the number of birds passing through the area at risk height, determined from survey data. Crucially, however, the model assumes that an individual bird takes no avoiding action when encountering a turbine, so an adjustment must also be made for avoidance behaviour. In this paper, we examine critically the estimation and use of avoidance rates in conjunction with the collision risk model (CRM). The sensitivity of predicted mortality to errors in estimated avoidance rates is assessed in three studies that have used the CRM. It should be noted that we consider only direct mortality caused by wind turbine collisions, but we accept that there may be other indirect effects on bird populations such as disturbance, displacement and loss of habitat (Langston & Pullan 2003, Percival 2005, Fox et al. 2006) that are outside the scope of this paper. CASE STUDIES
140 citations
TL;DR: In this article, the authors assess the degree of usefulness and the limitations of different remote technologies for studying bird behaviour in relation to bird-turbine collisions at offshore wind farms.
Abstract: Since the early 1990s, marine wind farms have become a reality, with at least 13 000 offshore wind turbines currently proposed in European waters. There are public concerns that these man-made structures will have a significant negative impact on the many bird populations migrating and wintering at sea. We assess the degree of usefulness and the limitations of different remote technologies for studying bird behaviour in relation to bird–turbine collisions at offshore wind farms. Radar is one of the more powerful tools available to describe the movement of birds in three-dimensional space. Although radar cannot measure bird–turbine collisions directly, it offers the opportunity to quantify input data for collision models. Thermal Animal Detection System (TADS) is an infra red-based technology developed as a means of gathering highly specific information about actual collision rates, and also for parameterizing predictive collision models. TADS can provide information on avoidance behaviour of birds in close proximity to turbine rotor-blades, flock size and flight altitude. This review also assesses the potential of other (some as yet undeveloped) techniques for collecting information on bird flight and behaviour, both pre- and post-construction of the offshore wind farms. These include the use of ordinary video surveillance equipment, microphone systems, laser range finder, ceilometers and pressure sensors.
126 citations
TL;DR: In this article, the authors present the results of spring and winter surveys of birds using 22 willow short-rotation coppice (SRC) fields and 22 paired arable or grassland controls over a 5-year period in central and northern England.
Abstract: We present the results of spring and winter surveys of birds using 22 willow short-rotation coppice (SRC) fields and 22 paired arable or grassland controls over a 5 year period in central and northern England. The study sites were linked to the first commercial wood-fuelled electricity plant in Yorkshire and were managed commercially. We use the findings of this study, in the context of other work on birds in energy crops, to suggest how birds may be affected by commercial cropping of SRC or energy grasses on UK farmland. For willow SRC, most existing farmland species were not completely displaced by SRC cropping. Even farmland specialists such as Skylark Alauda arvensis used cut SRC fields. Some species characteristic of scrub and wood-type habitats were attracted onto farmland by SRC. Birds were more abundant in hedgerows next to SRC than in those adjoining arable or grass. The interior of large SRC plots contained fewer birds than the edge-zone (< 50 m). In winter, the same resident species occured in SRC as the summer, plus winter migrants such as Snipe Gallinago gallinago and Fieldfare Turdus pilaris. Overall, more individuals and species were recorded in and around SRC than equivalent arable or grassland throughout the year. Yellow Wagtail Motacilla flava and certain locally occurring farmland specialists may be displaced by SRC plantations. Equivalent census data for energy grasses in the UK are not available. The impact of large regional energy crop developments on birds is not known. We do not know if species commonly recorded in these crops survive and breed well so population effects are unknown. However SRC crops are often weedy and insect rich and hence have potential as foraging habitats in summer and winter. The scope for agri-environment schemes to include energy crops is discussed.
91 citations
TL;DR: In this article, the importance of invertebrates for moorland-breeding birds and the conservation of such species in the UK is discussed. But the authors do not provide detailed experimental data with which to demonstrate the direct effect of particular moor land management prescriptions on some of these key invertebrate taxa for breeding birds, available data suggest that management regimes that create a mosaic of habitats are likely to be most beneficial.
Abstract: We reviewed the literature to determine the importance of invertebrates for moorland-breeding birds and considered our findings with respect to the conservation of such species in the UK. The diets of many moorland birds consist predominantly of invertebrates, with a wide range of taxa recorded in the diets of moorland birds during the breeding season. Relatively few taxa (Arachnida, Coleoptera, Diptera, Hemiptera, Hymenoptera, Lepidoptera and Oligochaeta) were widely taken, with Diptera and Coleoptera being the most important. Among these latter two insect orders, Carabidae, Curculionidae, Elateridae and Tipulidae were the most important families. Comparisons of the diets of bird families, treated separately according to whether data were derived from adults or chicks, showed that waders take more interstitial invertebrates than passerines, which themselves take more foliage invertebrates. Although we lack detailed experimental data with which to demonstrate the direct effect of particular moorland management prescriptions on some of these key invertebrate taxa for breeding birds, available data suggest that management regimes that create a mosaic of habitats are likely to be most beneficial. In particular, heterogeneity in vegetation structure and species composition, and the presence of wet flushes associated with the synchronized spring emergence of adults of certain insect species, are likely to increase invertebrate food resources for birds.
87 citations
TL;DR: The greater foraging effort of Boulders birds probably reflects reduced prey availability in False Bay, and thus the recent slowing in growth at the colony may be the result of differential immigration rather than management actions to limit the spatial growth of the colony.
Abstract: The African Penguin Spheniscus demersus (Vulnerable) formed three new colonies during the 1980s, two on the South African mainland (Stony Point and Boulders) and one on Robben Island. One of the mainland colonies, at Boulders, Simon's Town, is in a suburban area, resulting in conflict with humans. Growth of the Boulders colony was initially rapid, largely through immigration, but has since slowed, possibly as a result of density-dependent effects either on land (where there has been active management to limit the spread of the colony) or at sea. We test the latter hypothesis by comparing the foraging effort of Penguins feeding small chicks at island and mainland sites, and relate this to the foraging area available to birds. Three-dimensional foraging paths of African Penguins were reconstructed using GPS and time-depth loggers. There were no intercolony differences in the rate at which birds dived during the day (33 dives/h), in diving depths (mean 17 m, max. 69 m) or in travelling speeds. The maximum speed recorded was 2.85 m/s, with birds travelling faster when commuting (average 1.18 m/s) than when foraging (0.93 m/s) or resting at sea (0.66 m/s during the day, 0.41 m/s at night). There were strong correlations between foraging trip duration, foraging range and total distance travelled. Foraging effort was correlated with chick age at Robben Island, but not at Boulders. Contrary to Ashmole's hypothesis, birds from Boulders (c. 1000 pairs) travelled further (46-53 km) and foraged for longer (13.2 h) than did birds from Robben Island (c. 7000 pairs) and Dassen Island (c. 21 000 pairs) (33 km, 10.3 h). The mean foraging range also differed significantly between mainland (18-20 km) and island colonies (9 km). The area available to central-place-foraging seabirds breeding on the mainland is typically less than that for seabirds breeding on islands, but the greater foraging range of Boulders birds results in an absolute foraging area roughly twice that of island colonies, and the area per pair is an order of magnitude greater for the relatively small Boulders colony. Ashmole's hypothesis assumes relatively uniform prey availability among colonies, but our results suggest this does not apply in this case. The greater foraging effort of Boulders birds probably reflects reduced prey availability in False Bay, and thus the recent slowing in growth at the colony may be the result of differential immigration rather than management actions to limit the spatial growth of the colony.
TL;DR: In this paper, the authors studied the relationship between breeding success and nest fidelity in the white stork Ciconia ciconia, and found that pairs with higher fidelity rates also have lower failure rates and that breeding failure and productivity in previous season influenced the frequency of nest change in the following season.
Abstract: Nest-site fidelity is a life-history trait of birds that may produce benefits in terms of fitness. We studied the relationship between breeding success and nest fidelity in the White Stork Ciconia ciconia. We also studied how other factors such as age, sex, habitat, colony size and productivity in previous breeding attempts might interfere with this relationship. Our results showed that pairs with higher fidelity rates also have lower failure rates, and that breeding failure and productivity in the previous season influenced the frequency of nest change in the following season. In addition, a curvilinear relationship was found between age and nest fidelity. These results suggest that age is a major factor related to nest fidelity and therefore individual experience could explain this behaviour in the White Stork. Changing the nest involves a reproductive cost for which nest fidelity can be considered as an adaptive strategy to increase fitness.
TL;DR: In this article, the authors set the context for the development of tidal current technology in the face of impending climate change and so called "peak oil" and provided a general overview of the different technologies under development.
Abstract: This paper sets the context for the development of tidal current technology in the face of impending climate change and so called ‘peak oil’. Siting requirements are specified for tidal turbines and a general overview of the different technologies under development is given. Specific and detailed descriptions of leading Marine Current Turbine's technology are also highlighted. The paper considers the likely environmental impact of the technology, considering in particular possible (perceived and real) risks to marine wildlife, including birds. It concludes by indicating the planned future developments, and the scale and speed of implementation that might be achieved.
TL;DR: In this article, the influence of bird status (resident vs. migrant) and food availability (control nests vs. nests that benefit from high food supply) on reproductive success of Ciconia ciconia was investigated.
Abstract: In the mid 1970s, the breeding populations of the migrant White Stork Ciconia ciconia were close to extinction in the northeastern region of France (Alsace). A re-introduction project was implemented, resulting in the year-round settlement of some individuals in the region, which rely on additional food supplied by humans during the winter. Today, both resident and migrant birds breed in the same areas and take food from rubbish dumps and humans (farmers). The effects of these anthropogenic influences, altering Stork behaviour, on Stork reproductive success are not known. The aim of this study was to test the influence of bird status (resident vs. migrant) and food availability (control nests vs. nests that benefit from high food supply) on reproductive success. In control nests, the mean laying date was earlier in resident than in migrant White Storks. There was also a clear seasonal decline in clutch size. For all nests, the numbers of eggs and hatchlings were higher in resident birds than in migrants, which can be attributed to the earlier breeding of resident Storks. The large broods of resident birds showed a high mortality rate, leading to the same fledgling success (fledglings/hatchlings) and number of fledglings as in migrants. Fledgling success and the number of fledglings were higher for nests close to a reliable food supply. In summary, although resident birds can breed earlier and produce more eggs than migrants, we found no advantage in terms of number of fledglings. The higher mortality rate of chicks found in pairs with a large brood could be caused by the deterioration of their habitat. Thus, the year-round settlement of Storks may not present a biological advantage if the quality of their habitat is not guaranteed by the conservation of their grasslands.
TL;DR: Common Scoters were observed in lowest numbers or were absent from areas in which anthropogenic disturbance was relatively intense, even when these areas held a high prey biomass, and commercial fishing activities did not appear to contribute to this disturbance.
Abstract: Offshore wind farms are proposed around the coast of the UK and elsewhere in Europe. These sites tend to be located in shallow coastal waters that often coincide with areas used by over-wintering Common Scoter Melanitta nigra. A large-scale study was undertaken to ascertain the relationship of the spatial distribution of Common Scoter in Liverpool Bay with prey abundance and environmental and anthropogenic variables that may affect foraging efficiency. The highest numbers of Common Scoter coincided with sites that had a high abundance and biomass of bivalve prey species. There was strong evidence that the maximum observed biomass of bivalves occurred at a mean depth of c. 14 m off the Lancashire coast and at c. 8 m off the north Wales coast. This coincided well with the distribution of Common Scoter at Shell Flat, but less well with the distribution of birds off North Wales. Common Scoters were observed in lowest numbers or were absent from areas in which anthropogenic disturbance (shipping activity) was relatively intense, even when these areas held a high prey biomass. Commercial fishing activities did not appear to contribute to this disturbance.
Journal Article•
TL;DR: The interaction amongst information systems as a discourse is perceived and concepts from linguistics are used to outline different types of information systems interoperability.
Abstract: In this paper, we review the growing literature of interoperability typologies for information systems and propose an interoperability typology framework to provide a synthesis. For this we employ a metaphor fr om linguistics. That is, we perceive the interaction amongst information systems as a discourse and use concepts from linguistics to outline different types of information systems interoperability. The derived framework has been named Connection, Communication, Consolidation and Collaboration Interoperability Framework (C4IF).
TL;DR: In this paper, the effects of standard-quality (SQ) or lower quality (LQ) neonatal nutrition on components of fertility have been studied in Zebra Finches Taeniopygia guttata.
Abstract: Effects of neonatal nutrition on adult reproductive performance have been little studied. In Zebra Finches Taeniopygia guttata, poor neonatal nutrition is known to be associated with reduced blood antioxidant levels in adulthood, which could impair reproductive performance. Here, we compare the effects of standard-quality (SQ) or lower-quality (LQ) neonatal nutrition on components of fecundity. Compared with controls, LQ birds took longer to initiate egg-laying, and then laid eggs at a slower rate. LQ birds did not, however, show reduced clutch mass or size, or yolk antioxidant levels (retinol; α- or γ-tocopherol; carotenoids). Zebra Finches breed opportunistically, often only once in their short lifetime. Therefore, the timing but also the number and quality of eggs are critical fitness-related traits. Our results indicate that LQ birds had impaired reproductive capacity, suggesting resource accumulation constraints. Maximizing egg number and quality appears to have been more important than rapid egg production.
TL;DR: In this paper, the authors used mist-netting and direct observation of birds feeding at flowering plants to record the abundance of 16 species of hummingbird in lowland Amazonian rainforest.
Abstract: Many ecological theories predict a close match between food resources and the number and diversity of consumers but comparatively few empirical studies have simultaneously quantified seasonal variation in an entire assemblage and its resource base. Hummingbirds provide an excellent model system to examine this relationship because their primary food resource is conspicuous and easily quantified. Over a 2-year period I used mist-netting and direct observation of birds feeding at flowering plants to record the abundance of 16 species of hummingbird in lowland Amazonian rainforest. Although there was very little annual variation in temperature and daylength, both rainfall and river level showed significant seasonal variation. At the study site this resulted in an annual flood lasting for over 5 months, inundating much of the area to a depth of 2 m. I recorded marked seasonal patterns in flowering phenology and arthropod abundance, which correlated with river level and rainfall, respectively. In turn, these seasonal fluctuations in resource abundance correlated very closely with variation in hummingbird species richness, hummingbird abundance and the total biomass of hummingbirds in the assemblage. This study is the first to demonstrate tracking of seasonal resource variation in equatorial rainforest and provides evidence that hummingbirds are sensitive to resource availability at spatial and temporal scales much greater than previously documented.
TL;DR: This paper examined habitat correlates of Black Grouse distribution and population change from a 700-km2 area in the core of the Scottish range, where the numbers of lekking male birds declined by an estimated 70% to 270 between 1990 and 2002.
Abstract: Black Grouse Tetrao tetrix in Britain have declined through the 20th century, and most birds are now in Scotland. Many causes for this decline have been suggested, notably agricultural intensification, increased grazing levels and moorland afforestation. We examine habitat correlates of Black Grouse distribution and population change from a 700-km2 area in the core of the Scottish range, where the numbers of lekking male Black Grouse declined by an estimated 70% to 270 between 1990 and 2002. Habitat data were derived from satellite imagery, in combination with map and field-collected data. Lek occurrence, lek size and changes in lek size were all correlated with forest structure, either positively with the amount of pre-thicket forest cover, or negatively with closed canopy cover. Additional effects of the cover of grass moor and dry heath suggest that Black Grouse are most likely to occur where moorland comprises Heather Calluna vulgaris and grass mosaics. Analysis of the change in Black Grouse abundance within 1.5 km of discrete forest blocks suggests that forest maturation, which has been the dominant habitat change during the course of the study, alone accounts for 58–78% of the decline. Given the close association of Black Grouse and the occurrence of woodland (and particularly conifer plantation) throughout much of their British range, these findings can be used to inform the design of management schemes for the recovery of Black Grouse.
TL;DR: The results ran in the opposite direction to that expected, showing a positive correlation between mite load and plumage yellowness, which suggests that further work is needed to give clear evidence for a specific nature of feather mites, but Great Tits with higher mite loads had lower hatching and breeding success, which may support the idea that Feather mites are parasites.
Abstract: Plumicolous feather mites are ectosymbiotic organisms that live on bird feathers Despite their abundance and prevalence among birds, the ecology of the interaction between these organisms and their hosts is poorly known As feather mites feed on oil that birds spread from their uropygial gland, it has been hypothesized, but never tested, that the number of feather mites increases with the size of the uropygial gland of their hosts In this study the number of feather mites is considered with respect to uropygial gland size in a breeding population of Great Tits Parus major in order to test this hypothesis As predicted, the number of feather mites correlated positively with the uropygial gland size of their hosts, showing for the first time that uropygial gland size can explain the variance in feather mite load among conspecifics Previous studies relating feather mite load to plumage colour have suggested that feather mites may be parasitic or neutral To confirm this, the yellowness of breast feathers was also assessed However, the results ran in the opposite direction to that expected, showing a positive correlation between mite load and plumage yellowness, which suggests that further work is needed to give clear evidence for a specific nature of feather mites However, Great Tits with higher mite loads had lower hatching and breeding success, which may support the idea that feather mites are parasites, although this effect must be taken with caution because it was only found in males Age or sex effects were not found on the number of feather mites, and it is proposed that hormonal levels may not be sufficient to explain the variation in feather mite loads Interestingly, a positive correlation was detected between uropygial gland size and plumage brightness, which could be a novel factor to take into account in studies of plumage colour
TL;DR: Recoveries of birds ringed mainly in Germany confirm that irrupting Common Crossbills do not return to the boreal forest in northern Russia in the same calendar year as their irruption, but do so only in a later calendar year, when a new Norway Spruce crop is becoming available.
Abstract: Over much of Europe, Common Crossbills Loxia curvirostra depend primarily on the seeds of Norway Spruce Picea abies, and their breeding and movement patterns are governed largely by the cropping patterns of this tree species. Good cone crops occur only every few years in particular areas, but in different years in different areas. The main period of movement is in summer, when the previous year's crop is coming to an end, and a new crop is forming in different areas. In years when the Norway Spruce crop is poor over a wide area, and when Common Crossbills are abundant, they leave the boreal forest in large numbers, and appear as irruptive migrants in southwest Europe, with at least 40 invasions reaching Britain in the 120-year period 1881–2000. On irruptions the main migration axis is from northeast to southwest or west. Recoveries of birds ringed mainly in Germany confirm that these birds do not return to the boreal forest in northern Russia in the same calendar year as their irruption, but do so only in a later calendar year, when a new Norway Spruce crop is becoming available. The findings agree with an earlier interpretation of Common Crossbill movements, but not with an alternative hypothesis that irrupting Common Crossbills return to their region of origin in the same calendar year as the outward movement. Recoveries also suggest that some individual Common Crossbills may have bred in widely separated localities in different years (records up to 3170 km apart), and sometimes in localities far removed from their natal sites (records up to 2950 km apart.
TL;DR: In this article, the entire mitochondrial cytochrome b gene was sequenced to reconstruct the molecular intraspecific phylogeny of the Hwamei Garrulax canorus.
Abstract: Due to the male's elaborate songs, the Hwamei Garrulax canorus is the most popular caged bird in the global Chinese community. Three allopatric Hwamei subspecies have been described: G. c. canorus in central and southern China and northern Indochina, G. c. owstoni from Hainan and G. c. taewanus from Taiwan. We sequenced the entire mitochondrial cytochrome b gene to reconstruct the molecular intraspecific phylogeny of the Hwamei. Molecular phylogenetic trees indicated that individuals of the three subspecies formed three monophyletic clades with high bootstrap support (> 95%). The basal clade was G. c. taewanus. According to a conventional molecular clock (2% divergence per million years), G. c. taewanus split from the other Hwamei taxa around 1.5 million years ago, and G. c. owstoni diverged from G. c. canorus around 0.6 million years ago. Considering the periodic connection between the Asian mainland and nearby continental islands during the glacial periods, habitat vicariance may have played a more important role than geographical vicariance in facilitating the differentiation of these taxa. Molecular diagnosability, population integrity, and concordance between the population ranges and the topology of the phylogenetic tree suggested that the Hwamei should be delimited into at least two full species: G. canorus and G. taewanus. Our work represents one of the first attempts to re-evaluate the intraspecific systematics for an eastern Asian bird species using molecular data.
TL;DR: In this paper, radio telemetry on Sterna albifrons at their most important UK breeding site, the Great Yarmouth North Denes Special Protection Area (SPA), in relation to a 30 turbine offshore wind farm on Scroby Sands, which encroaches to 2.
Abstract: Many seabirds travel widely to exploit variably distributed prey resources, utilizing even profitable patches only briefly as prey become available. Assessing the relative importance of areas occupied by wind farms relies on sufficient survey effort to increase the probability of detection and later assessment to an acceptable level. Conventional techniques suffer from high sampling costs and infrequent sampling of patches within larger areas. Remote techniques, which continuously sample habitat, may offer a solution although sufficient coverage may be difficult to achieve. In this paper, we outline experiences of the use of radio telemetry on LittleTerns Sterna albifrons at their most important UK breeding site, the Great Yarmouth North Denes Special Protection Area (SPA), in relation to a 30 turbine offshore wind farm on Scroby Sands, which encroaches to 2 km from the North Denes colony. Little Terns had not been radio-tagged previously in the UK, and the technical difficulties of tagging and subsequently following a small (55 g) diving seabird limited data collection. However, comparative data from 2 years (2003 and 2004), in which the abundance of the terns’ preferred prey varied greatly, revealed striking differences in activity and foraging patterns, which changed the perception of the scope of the birds. With an active nest, birds occupied a range of < 6.3 km2 with a range span of up to 4.6 km. In comparison, failed birds ranged widely, occupying ranges up to 52 km2 and travelling up to 27 km in a single foraging bout. As birds were recorded from 2 to 3 km offshore, the wind farm is within range of birds from the breeding colony at North Denes, although only a small proportion of foraging time was spent at such distance in the years of study. The potential value of radio (and satellite) telemetry in illustrating habitat use, perhaps to set precautionary distance limits for wind farms as well as defining actual use of particular areas including for collision risk assessment is discussed.
TL;DR: In this article, the authors tracked 13 Golden Eagles Aquila chrysaetos during their first year of life using satellite telemetry and explored the distance to the nest attained during that period and the age at the onset of juvenile dispersal.
Abstract: Thirteen juvenile Golden Eagles Aquila chrysaetos were tracked during their first year of life using satellite telemetry. Distances to the nest attained during that period and the age at the onset of juvenile dispersal were explored. The performance of nine different criteria to determine that age was analysed. In general, after a brief period of restricted movements around the nest, the average distance to the nest increased with time. Maximum distances to the nest ranged between 57.7 and 184.3 km, and were considerably greater in females (mean ± sd, 138.5 ± 44.5 km) than in males (70.5 ± 14.0 km). No sex difference was observed in the age at which that distance was attained (males: 329 ± 32 days, females: 312 ± 20 days). The onset of juvenile dispersal took place around the fifth month of life (September in Spain). Eight of the nine criteria provided similar results, suggesting that in Spain dispersal starts when birds are between 140 and 180 days old, and that the post-nestling period lasts between 60 and 120 days. For future studies, to determine the age at which the onset of juvenile dispersal occurs, we recommend the use of either the first day on which individuals were located beyond the mean distance between nests of different pairs (10 km in our study area), or the date of the record midway between the first and the last location recorded during the month in which the maximum variability in the distance to the nest was observed.
TL;DR: In this article, the authors studied the use of saltpans and intertidal roosts by waders in the Tagus Estuary of Portugal during high water and found that most of the waders roosted in the saltpan during the peak of spring tides.
Abstract: During the highest spring tides the intertidal sediment flats of estuaries are fully inundated at high water, and waders have no choice but to move to supratidal roosts, e.g. on open farmland, saltpans or beaches. However, in many estuaries during the lowest neap or intermediate tides there are sectors of upper intertidal sediment flats that remain exposed even at the peak of high water, and so waders have the choice of roosting either there or in supratidal sites. In the Tagus Estuary, Portugal, as elsewhere, waders use both types of roosts during high water. Our main objective was to understand what makes waders opt for one of these two types of available roosts. We monitored wader use of saltpans and intertidal roosts from spring to neap tides, and measured foraging and alarm behaviour, prey availability and disturbance by predators. Most of the wader species studied chose intertidal (mudflat) roosts whenever these were available, and only roosted in saltpans during the peak of spring tides. We hypothesized that this preference was explained either by an attempt (i) to continue feeding into the high water period, or (ii) to minimize predation risk. Extending feeding time into the high water period did not seem to be very relevant for roost choice because both prey availability and foraging activity were low in both types of roosts. However, predator disturbance was several times higher in the saltpans than in the intertidal roosts, suggesting that this factor may be the determinant in the choice of roost type.
TL;DR: In this article, the authors present results based on 65 phylogenetically independent hybrid types from the western Palearctic, focusing on behavioural and ecological correlates of hybridization, and find a positive correlation exists between population size and the number of hybrids.
Abstract: Hybridization and speciation are central to evolutionary biology. Although birds have been studied more thoroughly than any other vertebrate class, there have still been few macro-evolutionary analyses. Here, I present results based on 65 phylogenetically independent hybrid types from the western Palearctic, focusing on behavioural and ecological correlates of hybridization. The main results are as follows. (1) Hybrids that are easier to detect were more often reported. (2) A positive correlation exists between population size (mean of both parent species) and the number of hybrids. After accounting for these confounding variables in a General Linear Model, I found (3) that sympatric species pairs produced fewer hybrids than did parapatric species pairs and (4) pairs with at least one of the parent species reported as endangered produced a greater number of hybrids whereas (5) species pairs with high male parental (paternal) care produced fewer hybrids. Other variables were excluded by a stepwise procedure in the following order: sexual dichromatism; body weight differences; publication bias. Phylogenetic information was available for a small number of hybrids but did not influence the results.
TL;DR: It is suggested that most species reacted moderately to habitat changes currently occurring, and this may be due in part to the fact that only a small proportion of the landscape at CMWMA has been converted to agriculture.
Abstract: In comparison with other tropical forest land uses such as selective logging, little is known of the impacts on wildlife of the many forms of small-scale agriculture practised across the tropics. We present density estimates, derived using a point count distance sampling method, for 31 bird species in primary forest, old abandoned gardens and active/recently abandoned gardens at two altitudes in the Crater Mountain Wildlife Management Area (CMWMA), Papua New Guinea. There were clear habitat differences between the six habitat/altitude categories, with, for example, clines in tree sizes and canopy cover from highest values in primary forest to lowest values in current gardens. At lower altitudes, primary forest held highest densities of most species, whereas at higher altitudes, old abandoned gardens had greater densities of many birds, especially insectivores. canoco was used to ordinate bird species with respect to major habitat gradient axes. Major axes were associated with differences in bird responses to forest conversion as well as altitudinal differences in species composition. Most important was that several insectivores (especially monarchs, fantails, etc.) formed a cluster of species associated with intact, high-biomass forest. We suggest that most species reacted moderately to habitat changes currently occurring, and this may be due in part to the fact that only a small proportion of the landscape at CMWMA has been converted to agriculture (around 13% may be current or recently abandoned gardens). There were, however, species with comparatively low densities in agricultural habitats and these included several insectivores, the terrestrial Blue Jewel-babbler Ptilorrhoa caerulescens, and three out of four birds of paradise.
TL;DR: The data suggest that EPC is beneficial to unpaired males but occurs at random in females, consistent with the hypothesis that EPP results solely from forced EPCs.
Abstract: Although 92% of avian species are socially monogamous, extra-pair copulation (EPC), resulting in extra-pair paternity (EPP), is a common reproductive strategy in birds. Among seabirds, in which the rate of social monogamy reaches 100%, Procellariiformes (albatrosses and petrels) show low EPP rates, with the noticeable exception of the only albatross investigated in this regard, the Waved Albatross Phoebastria irrorata . This species, in which forced copulations are known to occur, showed a surprisingly high rate of EPP (25% of chicks). We investigate here EPP rates in another albatross species, the Wandering Albatross Diomedea exulans , subject to a demographic survey conducted for 38 years. We combined data on pair bonds with analysis of ten microsatellite loci and found that 10.7% of 75 chicks had an extra-pair sire. Although there was some evidence for inbreeding avoidance, within-pair and extra-pair chicks showed similar levels of heterozygosity, and the incidence of EPP was independent of age, experience or past reproductive success. Hence, we found no evidence that females benefit from EPCs. Owing to the male-biased sex ratio in adults, widowed and divorced males required more time to find a new mate (+28 and +72%, respectively) than did females. Combined with high sexual size dimorphism, this phenomenon might promote the forced copulations observed in this species. Our data therefore suggest that EPC is beneficial to unpaired males but occurs at random in females, consistent with the hypothesis that EPP results solely from forced EPCs. However, the importance of the latter for EPP and the part played by solitary males require further investigation.
TL;DR: The habitat copying hypothesis states that animals use the reproductive performance of conspecifics to evaluate habitat quality and choose their future breeding site, and data from Audouin’s Gull Larus audouinii is used to analyse subcolony (as patch) choice within a colony to suggest this may be one of the strategies used by the species in selecting its breeding habitat.
Abstract: The habitat copying hypothesis states that animals use the reproductive performance of conspecifics to evaluate habitat quality and choose their future breeding site. We used data from Audouin’s Gull Larus audouinii (1992‐2003), a species adapted to unpredictable environments, to analyse subcolony (as patch) choice within a colony (small spatial scale). We also assessed the suitability of alternative hypotheses to the habitat copying hypothesis. The probability of subcolonies being reoccupied annually increased with their size (as number of nests), which suggests the existence of group adherence effects. Subcolony growth rate was related to its average reproductive success (or patch reproductive success) in the previous year: the higher the reproductive success in a colony, the higher the probability of growth the following year. However, this last result was obtained without considering the effect of colony size on the response variable because colony size is related to it. Therefore, results suggest at the population level that in this system habitat copying might either be one of the strategies used by the species in selecting its breeding habitat, or one of the possible strategies operating alone. The other strategies are group adherence mechanisms, and also the effect of conspecific attraction. At the individual level we failed to find evidence of habitat copying and only the previous success of an individual affected its fidelity to a subcolony. The importance of the lack of environmental predictability in the system is discussed, as predictability is a prerequisite of habitat copying.